An extrusion method and apparatus (11) for producing a cable (1, 101) including at least one core (7) comprising at least one transmissive element (2, 40), and at least one pair of coating layers (8, 9) arranged at a radially outer position with the respect of the core (7) are described. The method
An extrusion method and apparatus (11) for producing a cable (1, 101) including at least one core (7) comprising at least one transmissive element (2, 40), and at least one pair of coating layers (8, 9) arranged at a radially outer position with the respect of the core (7) are described. The method of the invention includes the simultaneous steps of depositing by co-extrusion at least one coating layer (8) of polymeric material and one coating layer (9) of expanded polymeric material and of maintaining a residual pressure not greater than the external pressure in a substantially annular interspace (21) defined between the coating layers. With respect to the methods of the prior art, the present invention allows to avoid the formation of bubbles at the interface between said at least one coating layer (8) of polymeric material and the coating layer (9) of expanded polymeric material, attaining an optimal adhesion between said layers (8, 9).
대표청구항▼
The invention claimed is: 1. An extrusion apparatus for producing a cable including a core comprising at least one transmissive element, and at least one pair of coating layers arranged at a radially outer position with respect to said core comprising an extrusion head, said extrusion head includin
The invention claimed is: 1. An extrusion apparatus for producing a cable including a core comprising at least one transmissive element, and at least one pair of coating layers arranged at a radially outer position with respect to said core comprising an extrusion head, said extrusion head including: a) a male die, a female die, and at least one intermediate die coaxially mounted between the male die and the female die around a longitudinal axis substantially parallel to an advancing direction of said core; b) a longitudinal cavity configured to receive said core defined in said male die; c) at least one pair of feeding channels defined in said extrusion head and intended for depositing by co-extrusion, respectively, at least one coating layer of polymeric material and one coating layer of expanded polymeric material a first feeding channel, defined in part by the male die, for depositing a first coating layer including a polymeric material on said core before said first coating layer exits said intermediate die, and a second feeding channel for depositing a second coating layer including an expanded polymeric material on said core after said second coating layer exits said female die; and d) a plurality of suction channels intended for sucking configured to suck the gases released during an expansion of said second coating layer including an expanded polymeric material, said suction channels being defined in said extrusion head between said feeding channels. 2. An extrusion apparatus for producing a cable including a core comprising at least one transmissive element and at least one pair of coating layers arranged at a radially outer position with respect of said core, comprising an extrusion head including: a) a male die, at least one intermediate die and one female die coaxially mounted between each other around a longitudinal axis substantially parallel to an advancing direction of said core; b) a longitudinal cavity intended for receiving said core defined in said male die; c) a first feeding channel, defined in part by the male die, for depositing a first coating layer including a polymeric material on said core before said first coating layer exits said intermediate die, and a second feeding channel for depositing a second coating layer including an expanded polymeric material on said core after said second coating layer exits said female die; d) at least one suction channel configured to suck the gases released during an expansion of said second coating layer including an expanded polymeric material; and e) a device configured to vacuum a fluid in communication with said at least one suction channel. 3. The extrusion apparatus according to claim 2, wherein said first feeding channel is arranged at a radially inner position with respect of said second feeding channel. 4. The extrusion apparatus according to claim 2, wherein said first feeding channel is provided with an outlet opening arranged in proximity of said longitudinal cavity so as to deposit said first coating layer including a polymeric material in reciprocal contact with said core. 5. The extrusion apparatus according to claim 4, wherein said second feeding channel is provided with a respective outlet opening arranged in proximity of said outlet opening of said first feeding channel so as to deposit said second coating layer including an expanded polymeric material in reciprocal contact with said first coating layer including said polymeric material. 6. The extrusion apparatus according to claim 2, wherein said at least one suction channel is interposed between said first feeding channel and said second feeding channel. 7. The extrusion apparatus according to claim 2, wherein said first feeding channel is also defined at least partly by said intermediate die. 8. The extrusion apparatus according to claim 2, wherein said second feeding channel is defined at least partly between said intermediate die and said female die. 9. The extrusion apparatus according to claim 2, further comprising a plurality of suction channels equally spaced with respect to said longitudinal axis. 10. The extrusion apparatus according to claim 9, wherein geometrical centres of cross-sections of said plurality of suction channels lie on the same circumference coaxial with respect to said longitudinal axis. 11. The extrusion apparatus according to claim 2, wherein said at least one suction channel is axially formed in said intermediate die. 12. The extrusion apparatus according to claim 2, wherein said at least one suction channel has a substantially circular cross-section. 13. The extrusion apparatus according to claim 2, wherein said at least one suction channel has a substantially rectangular cross-section.
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이 특허에 인용된 특허 (17)
Takeno Kazuta,JPX ; Ito Takeo,JPX ; Kasahara Shigeo,JPX ; Takayama Gen,JPX ; Kaneko Hiroshi,JPX ; Sakai Yoshiyuki,JPX ; Kusago Toshihiko,JPX ; Iguchi Katsuhiko,JPX, Apparatus and method for applying a coating to a base material.
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